Two-temperature refrigerator with automatic defrosting



Aug. 4, 1953 E. w. zEARFoss, JR

TWO-TEMPERATURE REFRIGERATOR WITH AUTOMATIC DEFROSTING 3 Sheets-Sheet 1 Filed May 13, 1950 1953 E. w. ZEARFOSS, JR 2,647,375

TWO-TEMPERATURE REFRIGERATOR WITH AUTOMATIC, DEFROSTING Filed May 15, 1950 a Sheds-Sheet 2 F/G. Z.

INVENTOR.

WOZNZvM Aug. 4, 1953 E. w. ZEARFOSS, JR

TWO-TEMPERATURE REFRIGERATOR WITH AUTOMATIC DEFROSTING a Sheets-Sheet 3 Filed May 15, 1950 INVENTOR.

[1/1/57 M. ZZA/PFO/f J:

AMA 7'1 Patented Aug. 4, 1953 mrso PATENT QFFTICE :poration-of Pennsylvania The invention hereinafter disclosed ahd ciai'iineli sums to refrigeration and, mm apartifilblfly, is westerneifiifih rerrigeiatons the plural coinoar trnent tyhe mai ing qa'rovi-sion {for automatic removal or ifrost seposited upon the surfalfies of the vai'porator or other'element utilized to prod-u r irigeration.

summin fihe invention it "is to be borne in mifid it is now wen recognized. math is desirable provide within refrigerated cabinet mot only a main storage icomp artment maintained at temperatures above the freezing point of water, in order to @srovidefor the-proper preservation of fresh fruits, vegetables and other foodstuffs which should not he subjected to-"subfreezing temperatures, hut also a mompartment maintained at sub-freezing temperatures -suitable for the preservation of frozen foods "over long ,-pe1:iod's of time. The temperatures desirable in the irozen food compartment irequently range well below 0:F.*and, as will be appreciated, maintenance :of temperatures in this region has created problems in reirigerating the warmer compartment without reducing its tempera-.

tine-particularly during periods of relatively infrequent useto a value sueh that the :iiuits andve tahles stored therein becbihe'irozen.

Several difi-erent approaches have been made to thi problem per ps the iii'dst satisraemy n th us horizontal artiti dr baflle which divides the space def ned By thei nn erlinenof the cabinet into upper and lbvver food storage compartrnents andwhieh limits, {but does not eliminate, the circulation (Stair between said upper and lower compartments. In arr-a 'gements of this type, which ar highly satisiacto ry from 9. Enumberof points oi view, the limited simulation of air referrd'to may be relied upont'o accomplish refrigeration of the main, higher temperature eoinpartrnent, the ow temperature evaporator either being disposed within or constituting the other e'ompa eased takingcare of'the fr'oien food require ents, 'W-hile such "constructions have broven 'aav npagdusgthey have not, he-retofo're, teen sfipieteiy shimmery, toartieularly in; atfniois'ture brseiit'inthe niain higher temper ure conipartnien isf-dhositeduhon'thesubfireezi'ng'vap oi'iator, miss "other compartm nt, in-the form oiifrost, thus necessitating periodic shutting down of the refrigerating system -for defrostin g purposes. Extended-discontinuitiesof operation ofr-the systeml tend, ofzcourse, to result in. thawing; of: the efrozn foods with attendant deteriorationfithereflf onizinvaddititm; the de in the ca net of "a generally a frosting operation has ireqii'entiy =-been trouble some "and *"tinie-bonsuming. It also to he understood thatthvhalile *or'qaar-tition must impede the fiownf-"airhtween the tttoqforrigifitments to --an extent insuring "suflle'iently lhigh temperaturesin tl'iehiainibdd storage-transmitment "and this ifactor;in turn, introduces'andther problem in that the "temperature *retovery time of *saidmai'n eompartmenvis not as "rapid as "it should be. "That is, under honditions'wlim access is irequehtly had to the main storagewompartmeht and the temperature 'th'ereof L is therefore unduly elevated 'bythe inflowof warm air ftoin the *ro'om'in "which the-refrigerator is located, the'interchange-of airbetween' the two'oompartments may not he l-sui ficiently' rapid, under such conditions, to maintain the desired "temperature in the main compartment.

Attempts have also :been made to meet 'the basicdifficulties outlined aboverby effectingsubstantially completeisolationrof the two' compartments, both thermally-and from the-standpoint oi-interchange ofair. This expedient "has the advantageof, reducing the frequency 'of, but-not eliminating -the defrosting operation. However such-attempts have been unsatisfaetory fr'om the over-all *poi-nt of view; because of "the fa'ct that such isolation of the compartments permits the moisture to become excessively high-inthe main food storage compartment, "with resultant condensation onthe walls and 'othersurfaces 'exposedtherein; I h v By the-present invention there is -provided;a refrigerator wh-ich has the advantages of, both modes of refrigeration outlined above, andayet is not subject to the "attendant disadvantages described. In *accordance with my invention,,-a mm 91 ar i n isfiii e 1-t w s in r ling the degree of heat e geha ng e between the two compartments the cooling of both-compartmentsis effected through the agency of a single 3 9 13 911 which P vQY jWl' .1 11? p a n of frozen foods, and the afpresaid arrangement includes, in novel combination therewith, means forlfe'cting autornatic defrosting of the evapor'ator'w ith rapids such thatjthi'e is no-ihterferencelwit'hitlie preservationof frozen foods and with little or no attention required upon thepart of the user.

It is alsoan important object of this invention from the evaporator, without interfering appre cia-bly with the "tempefatiires nornially maintained within the higher tem'peratu-re am; pertinent.

It is a feature of the invention that removal of excess moisture from the higher temperature, main compartment is provided for automatically under conditions when the relative humidity of said compartment is apt to be unduly high, such removal being effected through the agency of novel means cooperable within the partition or baffle to control the degree of heat exchange between the two compartments.

Apparatus constructed in accordance with my invention is further characterized in that the heat exchange which it is possible to effect between the two compartments becomes, under conditions of very frequent use of the cabinet, sorapid'that recovery of temperatures inthe warmer orlmain storage compartment is no longer a matter of concern.

In the achievement of the foregoing general objectives, the apparatus of this invention, in its preferred embodiment, comprises: a bafiie -or partition disposed within the refrigerator cabinet and'separatingthe space therein into a pair I of compartments or zones, one of which is adapted to be maintained under temperature conditions suitable for the storage of foodsat sub-freezing temperature'sand theother of which is adapted to be maintained under temperature conditions suitable for the storage of foods at above-freezing temperatures, said partition being shaped and disposed-within said cabinet. to provide for limited circulationof cooling air between said two compartments; an evaporator for cooling the sub-freezing compartment as well as the air circulated between the two compartments; a heater effective to melt the frost deposited upon the evaporator; and air propelling means, preferably a propeller 'type fan, operable to cause a circula tory flow of air between a restricted zone of said warmer compartment, past said heater and evaporator, sequentially, and back to said zone of the warmer compartment. The fan is further effective, when the temperatures of the warmer compartment require it, to produce a relatively' unrestricted flow of air between the said two compartments, the heater not being energized; "Considered'with more particularity, and in accordance with a particular feature of the pres-" ent'invention, the flow of air induced by the fan,

under normal cooling conditions, that is, when a defrosting operation is not in progress, is acirculatory flow through or around the baflie and siderable extent. Rather, the flow is then through a restricted zone to one side of said space; that is, closely adjacent to the partition. Under such conditions, the circulating air is-'-due to the action of the aforesaid heater-of considerably higher temperature than the air normally present even in'the warmer compartment and, as will appear more clearly in the following detailed description, the shallow circulation which takes place in'the'warmer compartment during defrosting, results from stratification of the colderair' within the lower (higher temperature) compartment and consequent lack of interference with the temperatures desired in said compartment. It

is particularly to be noted that this advantageous result is secured without the necessity of providing any dampers or other air-110W (19111101 means in said partition. r

The manner in which the foregoing and other objects and advantages of my invention may best be achieved, will be fully understood from a consideration of the following detailed description taken in conjunction with the accompanying drawings, in which:

Figure 1 'is'a' sectional, view taken generally through the vertical mid-plane of a refrigerator embodying the invention, certain control circuitry being illustrated diagrammatically;

Figure 2 is. a view, on an enlarged scale, of the upper portion of the apparatus illustrated in Figure 1, and indicating the nature of the circulatory air flow'induced by the fan and partition under defrosting conditions;

Figure-3 is a sectional view taken in the direction indicated by the line 33 of Figure 2, and

Figure 4 is an exploded, perspective illustration of the evaporator and baflie assemblies utilized in the embodiment illustrated in Figures 1 t0 '3.

- Now making more particular reference to the, drawings, and especially to Figures 1 and 2 there-.

of, it will be seen that the invention is therein illustrated as embodied'in a domestic refrigerator comprising an outer shell I0 and an inner shell or liner member I I, spaced inwardly of and insulated from'the outer shell III by any suitable insulation, shown at I2. As is customary, a breaker strip I3 of low thermal conductivity extends about the forward edge of the cabinet and bridges the gap between the outer'shell .III and the. inner liner I I. The refrigerator also includes a compartment I4 housing a compressor unit of any desired type, and a condenser I5 is disposed in the form of a flue extending upwardly along the back wall of the outer shell I0.

sired type and, as will be understood, are connected in refrigerant flow circuit with an evap-' orator shown at I6, the conduits being omitted from the drawings to simplify the same, and in" view of the fact that the invention is not concerned with the sealed per se.

As clearly appears in both Figures 1 and 2, the

refrigeration system,

space within the inner liner I I is sub-divided into numeral I9. The partition is of novel construc-- tion and will be further described inwhat follows, The front access opening of the cabinet is provided with a door 20 adapted to seal the space defined by the inner liner, seating against the cabinet in the plane of the aforesaid breaker strip I 3.

The upper zone or compartment I1 is utilized as the cold compartment adapted for the storage of frozen foods, as indicated hereinabove, and

the evaporator I'B, which is illustrated as bein of U shaped configuration, occupies substantially all of the space within said upper com- In the illustrated embodiment said partment. evaporator actually comprises said compartment, but it will be appreciated that such need not necessarily be the case, since the compartment may, for example, be cooled through its walls.

The underlying, warmer compartment I8 may andpreferably does receive at least some refrigeration by virtue of heat exchange effectedthrough the partition I9 and the material of the: 'P IP UQI .fl l 1 116 on truction thereof are suchv The com-' pressor and the condenser may be of any de- 5. as totpresentza desired. de ree of hermal. .ime nedance-adoenoat-he partition as dou l '1 oanstructione Additionally, the upper wall ghthereof as preferablyraioricated ofisheet metal. 01. example aluminum, ;-the purpose 2 of willibemlear from what follows; As clearly. appears in; thezdiawingsyrthe partition iswprovlded, inthe central portion; of its rear edge, with a gen erallvzsemieiiicular .opening 22. within which: is received iaycii culartcollar member 23, whichla'tter appears to-best advantageinFigure .4. There. is

I treedom; tor limited circulation of air across the front-=- edgez' of 'the partition; .sthrough the gap shown= at.14 .(Figure 2) thereby nirtherprom-oting therdesired degree ofthermal exchange K be.- tween. the? two compartments: This gapis also employed; in'a novel manner during the defrosting operation. l

The partition is inclined slightly toward the rear ofthe cabinet. to pn'lmote drainage of-moisture-receivedion theupper surface thereof during' :the defrosting operation, and 1 'inoisture .so delivered flows through "apertures shown at 25, and thence downwardly in any convenient mannerfordelivery to a surn'p or Teceptaelefiii. A smallrnotor 2! is mounted within the upper; oompartment, this motor-driving a fan 28 disposed within the aforesaid collar 23, and hence lying inthe general plane-ofthe partition.

'As shown in Figure 4, the partition is su'pported through the agency-of a'pair of opposed guide rails 29-49 which may: be fixedly secured to the side walls of the inner liner in any desired manner, and from which guide rails the partition may readily be withdrawn for cleaning purp se g Asalsoappears to bestadvantage in Figure {1, the evaporator I6 is provided, about the lower edge thereof and also about the'front vertically extending surfaces thereof, with, ineans 35! adapted to seal'against adjacent, wall surfaces of "the inner liner and thus minimize access of moisture-laden air to all but the lower surface of said evaporator. Byvi'rtue of this seal .(it further being notedthat the evaporator isfprqvicled with a door 3l the deposition of; frost upon said evaporator is limited to the downwardly presented surface thereof, which also comprises the sole surface having substantial effect t l n of the l wer compar ment Disposed intermediate thissurface of the evaporator'and the partition I9, is a heater element 32 which latter is preferably of the metalcl ad type sealed against the entrance of air and moisture. Insofar as the broader principles of the present invention are concerneithisheater element may take other, forms, although th illustrated embodiment has provenyery satisfactory fo the purposes of the invention; Heater sz is provided \vithend terminals 33 and 34 adapted forconnection to electrical circuits, dfiecribed hereinafter. When the heateris energized, that is, when defrosting is required, the metallic s e t 2! which comprises the upper surface of the partition reflects the heat upwardly toward the under-s'ide of the evaporator, thereby erpediting the defrosting-operation and aiding in the prevention of interference-with the'ref -igeration temperatures desired in the lower compartment Under normal refrigerating conditions, when automatic defrosting is not requiredythe'heater' 3215 not energizedand thedower compartment tfli; is -cooled by heat exchange effected through andwaround the partition l9; Under. such con-1 6 difiOnS;;\ail$. flQW5 upwardlyalong the door 2.9, inwardlnthroughthe gap 2.4,11thence inheat ex; changeorelation-withuthe lower portion of the evaporator: t6 and downward-1y through the par ti-tionaperture .'22,. through the blading of fan 2-8. As indicatedlatlar in. this.description,,pr0vision is madeito actuate the fan 28. in response to increase in temperature of the compartment I8, above a. predetermined value and, since it s advantageous to gprovide..fcr relative low velocity ofthe air as it moves downwardly. within the compartment 1.8;the fan rotates insuch adirection .as .to move the air upwardly therethroughin oppositionto the normal convective flow of air withinthe cabinetand to eject the cooled air through thegapfl, from whence it flows Well downwithin the compartment [8, as represented by the arrows shown. at Figure 1.

It is a particuIar feature of this invention that the fanis also efiective to prevent excessively high humidity Within said-compartment is since, umler. conditions whenoperation of thefan s required, thehumidity within said compartmen tends to behigher than under conditions when the fan is not-needed. The truth of this will b seenwhenit is recognized that, most frequently, operation of the fan willbe initiated after the main door has been opened. a number of times within a relatively briefperiod, and it is under such usageconditionsthat moist airgains access tothe cabinet. Excess moisture is of course deposited along the lower surface of theevaporator I6. and, when the deposit has reached a predetermined thickness, or whenthe apparatus has been in operation for a'predetermined period time-it becomes desirable to remove the frost. As indicated in that portion of this descriptio having to do with the electrical control circuit, defrosting maybe initiated, in any convenient manner insofar as the requirements of the presentinventionzare concerned.

Prior to av description .of the functions of the apparatus under. defrosting conditions, the electrical circuitry should be understood; The circuitdeS'oEibed just-below is satisfactory, but it. is to .beiunderstood that, insofar as the concepts of this invention are (concerned, the circuitry is merely-indicative of one convenient mode .of achieving, the functions desired. Basically, the invention contemplates. controllingthe operation of the-tan eitherin response to the temperature ofathe air in compartment 18, or when defrosting isdesire'd...

It will benoted. that the refrigerator is provided ith apair of. temperature-responsive control elements. 35 and. .36, each of .said elements, throughthe agency of conventional control bulbs, being adapted to initiate operation of instrumentalities'wi-th-in the system. Element 35, for example, is provided witha control-or feeler bulb 3 disposed in heat exchange relation with the evaporator 55. .When the. temperature of the evaporatorahas risen sufficiently-to expand the bellows-of e1ement35, the contacts of switch 38 are'closed,thusplacing the compressor 42 across thetline through the. movable blade 38 and the right hand contact on of a manually adjustable double pole, double throw switch 4|; Similarly, bellows element 36 is provided with a feeler bulb 43 and, when-the temperature of the compartmerit 18 (has risen to a predetermined value, expansion-of-bellows toclosesthecontac'ts of an associated i switch .44 and. causes energization of the fan 28. toy-closing a circuitincludingmovable blade 39c, contact, 41112, contacts llaiid, through the agency of contact '40 and movable blade 39, to one side of the line. The circuit to the other side of the line is completed through a dooroperated switch 45, of known type, which is maintained in closed position when the refrigerator door is closed, and which switch is adapted to open the circuit to the fan 28 when the main door is opened. As will now be understood, provision is made for rapid and automatic defrosting of the evaporator I6 and, when such is desired, blades 39 and 39a of the manually settable switch 4| are moved until they bear against contacts 40a and 400, re-- ,spectively. When this adjustment has been made the heater 32, as well as the fan 28, are placed directly across the line (the fan through the agency of door switch 45) and the circuit to the compressor 42 is opened, regardless of the position of the bellows element 35 with respect to its associated contacts. In the illustrated embodiment such manually initiated defrosting has been shown for purposes of simplicity of illustration, butit is to be understood that the invention also contemplates utilization of automatic means, such as a timer, for energizing the heater 32. This may, of course, be accomplished in a variety of ways which need not be described herein.

When the switch 4| has been adjusted in such a way as to initiate the defrosting operation, the fan 28, which is also in operation under such conditions, draws air upwardly from compartment l8 through the relatively restricted opening 22, passes said air in heat exchange relation with the heater 32 and the lower surface of evaporator l6, after which the air flows downwardly through the aforesaid gap 24. As mentioned hereinabove the downfiow of air through said gap occurs at a relatively low velocity, because of the greater area of said gap as compared with the area of the opening 22, this being of importance in that it promotes stratification of air within the lower compartment I8. The arrows applied to Figure 2 represent the relatively shallow air flow which obtains under such conditions, thisshallow flow resulting from the fact that the circulating air due to the action of the heater 32is at an elevated temperature with respect to the colder air which has stratified within the compartment l8. As a result of this novel construction, and the stratification of air which results from the use thereof, it is possible to defrost the evaporator l6 without any appreciable interference with the temperatures desired in the lower compartment and, importantly, without the need of dampers or other means to close the gaps normally presented through and around the partition. 1

In practice excellent results have been obtained by supplying about 650 watts to the heater, and utilizing a motor of 0.0015 H. P. operating at 3,000 R. P. M. and driving a four-bladed fan, three inches in diameter. It is to be understood that the cabinet, evaporator and the other components of the refrigerator are of a size normally utilized in the practice of household refrigeration. The gap 24, in the illustrated embodiment'has a cross-sectional area such that, using a motor and fan assembly of the type specified, the air flow through said gap is equal to approximately 15 GE. M.

Approximately 0.5 pound of frost has been removed'from the evaporator of this system in a period of about 8 minutes, and without raising the average temperature of the air within the lower compartment more than about 1 F. While defrosting of the evaporator also takes place without undue elevation of the temperature of the evaporator I 6, it has been found convenient to utilize a support, or trivet 41 (Figure 2) disposed within the evaporator, this trivet being of low thermal conductivity and comprising the surface upon which frozen foods are supported. By the use of this device any possibility of interference with the proper preservation of frozen foods within the evaporator I6 is eliminated In the light of the foregoing description it will be understood that by the present invention there is provided novel and advantageous refrigerating apparatus of the two temperature, automatic defrosting type. All of the advantages of the relatively inexpensive baffle-controlled re- :frigerator have been retained, and yet the apparatus is of uch a type as to require no attention during defrosting, to be characterized by unusually good temperature recovery within the main food storage compartment, and to be highly effective in removing moisture from the main or higher temperature compartment, under conditions when the humidity therein is apt to be excessively high.

While a single embodiment of my invention has been illustrated, and described in this disclosure, it will be understood by those skilled in the art that the invention is susceptible of changes and modifications without departing from the essential concept thereof, and that such changes and modifications are contemplated as come within the terms of the appended claims.

I claim:

1. A baflle or partition assembly adapted for use in refrigerators, said assembly comprising: a relatively flat, heat exchange wall, one edge of said wall having a re-entrant portion constituting an aperture through the wall, a member having an annular flange portion and bearing portions extending substantially at right angles with respect to said annular flange portion, said annular flange portion being removably disposed within said aperture and said bearing portion contacting side surface portions of said wall.

2. In combination with a refrigerator cabinet, baflie structure comprising a heat exchange partition three side edges of which are disposed closely adjacent to walls of the cabinet and one side edge of which is spaced from a wall of the cabinet, whereby to provide for interchange of air between the spaces lying to either side of said partition, said partition further being provided with an aperture extending therethrough, and air propelling means cooperable with said aperture to provide for forcible circulation of air through the aperture. I V I 3. In refrigeration apparatus, a cabinet, a bailie or partition disposed within. said cabinet and separating the space therein into a pair of superposed compartments or zones the upper of which is to be maintained at freezing temperature condition and the lower of which is to be maintained at temperature conditions suitable for the storage of foods at above-freezing temperatures, said partition being so shaped and disposed within said cabinet as to provide for limited circulation of cooling air between said two compartments, cooling means disposed in heat exchange relation with the upper compartment and presenting surface portions therein upon which moisture is frozen during normal operation of the apparatus, means for supplying heat in the region of said surface portions when it is desired to melt the frost accumulated thereon, and air propelling means cooperable with the partition agcrvgsrzs tocause a circulatory flow of air from'the region jnstbelow saidxpartitionuto said upp '-cfimim t+ merit, the air'passing. in 1 exchange relation with said heating means and .saidasurfacemon tions and thereafter returningto the-said region just below. saidipartition for reacirculation, said air,.,as it passes beneath said'partition; beingcom fined to .the. said region :by virtueiof its higher temperature 1 i and consequent lower density, compared with the temperatureiand ,densityicf theair-in'lower. regions.of.=the said lower compartment.

4.-' =Refrigeration apparatus in accordance w ith claim 3, and further characteriaed in that the air propelling means is automatically operable in response to energization of saidheatingmeans. 5.1 Refrigeration apparatusingaccordancesgith claim 3, and in which: said CQQliIl me generally U shaped configuration the lowe of saidcooling means constituting the ,surface portion and substantially,spanningathe distance-between-vertically extending Wall fthe upper compartment, and in which apparatus there is further included means 'cpoperable, with said cooling meansandthe walls of the ppmpar'tment to confine access" of moisture-laden air -to the said surface portions only.

6. Refrigeration apparatus in accordance with claim 3, and in which the partition is configured to provide at least two spaced openings each communicating with both compartments, one of said openings being of relatively small cross-sectional dimensions, and said air propelling means being effective to draw air upwardly through said one opening, and the other of said openings being of relatively large cross-sectional dimensions whereby said air propelling mean is effective to cause the air to flow downwardly at low velocity through the opening last mentioned, in returning to the region below the partition.

7. In a refrigerator, walls defining a cabinet having a partition therein dividing the space within said cabinet into an upper sharp-freezing chamber and a lower food storage chamber, a refrigerant evaporator disposed within said upper chamber and substantially spanning the distance between walls thereof, means cooperable with said evaporator and with walls of the chamber to confine access of moisture-laden air to certain surface portions of said evaporator, whereby frost may collect upon said surface portions only, said partition being provided with an aperture and further including an edge portion spaced from a wall of the cabinet to provide for passage of air around said edge portion and consequent circulation of air between the upper and lower chambers, heating means disposed within said upper chamber in proximity to the said surface portions of said evaporator, and a fan disposed within said aperture and cooperable with said partition to effect a circulatory flow of air from said lower chamber past the heater and the said surface portions of the evaporator, and thence returning to the lower chamber for re-circulation.

8. In refrigeration apparatus, vertically extending wall structure defining a substantially rectangular cabinet adapted for access from the front thereof, a bafile or partition disposed within said cabinet and separating the space therein into a pair of superposed compartments or zones, the upper of said compartments being provided with a generally horizontally disposed regrigerating evaporator, said partition substantially spanning the distance between opposed side walls of said cabinet and being so shaped and disposed within said cabinet as to provide for limited pas sage -otaii' between said two compartments through the regionof boththe front and the rear edges of said partition, and means for maintrainingsaid lower compartment at above freezing temperaturessuitable for the storage of fresh foods,;- said -.means comprising: air propelling means coope rablewithsaid partition to withdraw air-iromsaid lower compartment upwardly at therear portionof the partition and to force said ai-rthrough the upper compartment in heat exchange relationftvith said evaporator, the 0on str'uction and arrangement being such that air se-forced now s toward the front of the compartment be tween thepartition and the evaporator andisre-injected into the upper portion of said lower compartment by passing downwardly at the forward portion of the partition directly to the regions just below said partition.

I 9.-In s refrigerator including evaporator means normally maintained at sub-freezing temperatures-and-upon which frost collects, part1 tion meanstdisposed in adjacency to said evaporator-means -me'ansfor removing the frost from saiclevaporator means, comprising: air heating meansf and-air propelling means automatically operable iii-response to energization of saidhea-ting means and cooperable with said partition means to produce a relatively low velocity circulatory flow of air from the space between said evaporator means and said partition means, through the space adjacent the opposite side of said partition means, said air, as it passes through the second mentioned space, being restricted to a region in close adjacency to said partition means by virtue of its low velocity and the stratification of air resulting from the thermal gradient existing from said partition downwardly.

10. In a refrigerator including evaporator means normally maintained at sub-freezing temperatures and upon which frost collects, partition means disposed in adjacency to said evaporator means, means for removing the frost from said evaporator means, comprising: air heating means disposed between said partition means and said evaporator and in spaced relation with respect to each thereof; and air propelling means cooperable with said partition means to produce a relatively low velocity circulatory flow of air from the space between said evaporator means and said partition means, through the space adjacent the opposite side of said partition means, said air, as it passes through the second mentioned space, being restricted to a region in close adjacency to said partition means by virtue of its low velocity and the stratification of air resulting from the thermal gradient existing from said partition downwardly.

11. In a refrigerator including evaporator means normally maintained at sub-freezing temperatures and upon which frost collects, partition means having an aperture extending therethrough, said partition means being disposed in adjacency to said evaporator means, means for removing the frost from said evaporator means, comprising: air heating means; and a fan disposed within said aperture and cooperable with said partition means to produce a relatively low velocity circulatory flow of air from the space between said evaporator means and said partition means, through the space adjacent the opposite side of said partition means, said air, as it passes through the second mentioned space, being restricted to a region in close adjacency to saidpartition means :by virtue of its low velocity and the-stratification of air resulting from the thermal gradient existing from said? partition downwardly. 7-

12. In refrigeration apparatus, a cabinet, a baflle or partition'dlsposedsubstantially horizontally within said cabinet and separating'the space therein into an upper relatively small compartment and a lower food'storage compartment of relatively large size, the upper of -said compartments having cooling means in heat 'exchangerelation therewith, and said partition'being so shaped anddisposed within said'cabinet as to provide for limited circulation of airbetween said two compartments, and means for maintaining said lower compartment within a predetermined temperature range and for defrosting said cooling means ofthe upper compartment, said last means comprising: air propelling means; means for heating said cooling means; and apparatus for controlling said air propelling means and said heating means, including, means rendering the heating means operable when defrosting of the cooling means is 12 air propelling means, when energized being 00- operable with the partition to withdraw air from said lower compartment and to force'saidair into the upper compartment in .heat exchange relationwith said cooling means, the: construction and arrangement. being such that 'the' airl so forced is reinjected directly into the upper portion of said lower compartment by being passed from said upper compartment to the region just below said partition.

' ELMER W. ZEARFOSS, J n;

References Cited in the-file of this patent UNITED STATES PATENTS Date Number Name 1,913,433 Doble June 13, 1933 1,956,070 Hokanson Apr. 24, 1934 2,008,628 Ruff July 16, 1935 2,080,387 Hayes May 11, 1937 2,089,608 Horlacher Aug. 10, 1937 2,124,268 Williams July 19, 1938 2,126,285 Schafi Aug. 9, 1938 2,178,336 Chapman Oct. 31, 1939 2,506,448 Gregor May 2, 1950 2,511,419

Smith 1 June 13, 1950 

